Grid glow tube



' June 13, 1939. D. D. KNOWLES 2,162,508

GRID GLOW T UBE Filed Feb. 20, 1937 WITNESSES: INVENTOR v Dewey Q Know/e5. M

ATTORN EY Patented June 13, 1939 UNITED STATES PATENT OFFICE GRID GLOW TUBE Pennsylvania Application February 20, 1937, Serial No. 126,900

12 Claims.

My in ention relates to electric discharge apparatus and it has particular relation to discharge apparatus of the type incorporating gaseous electric discharge devices.

In gaseous electric discharge devices, the discharge produced is of the arc-like type. That is to say, the discharge is formed abruptly and cannot be extinguished except by the interruption or the reversal of the potential whereby it is supported. A gaseous discharge device of the type incorporating a control electrode is normally decnergized for a given anode-cathode potential until the control potential rises above a critical value. At this point the discharge is initiated. However, once the discharge is initiated it cannot be extinguished by simply decreasing the control potential below the critical value. The anodecathode potential must be either interrupted or reversed.

While the latter property of gaseous discharge devices does not offer difiiculties when the anodecathode potential is of the alternating-current type, an entirely different situation is involved where only direct current is available. In the direct current systems of the prior art of which I am aware, once a gaseous discharge device is initiated, it cannot be deenergized without interrupting the main supply.

It is accordingly an object of my invention to provide a system for operating a gaseous discharge device from a direct-current source wherein the discharge device once energized shall be capable of deenergization without interruption or reversal of the potential of the source.

Another object of my invention is to provide a system incorporating a gaseous electric discharge device having a control electrode in which the principal potential supplied to the discharge device is of the direct-current type, and in spite of this fact, the discharge device is continuously responsive to the influence of variations in its control potential.

More concisely stated, it is an object of my invention to provide a system incorporating a gaseous discharge device having a control electrode that shall be completely operable from a direct-current source.

According to my invention I provide an additional gaseous discharge device which is normally maintained in a condition diiierent from that of the discharge device under control. The two discharge devices are coupled to each other through a capacitor or similar means which operates to impress the necessary potentials between their principal electrodes to produce an interchange in their conditions when the condition of the controlled discharge device is changed.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing, in which the single figure is a diagrammatic view showing an embodiment of my invention.

The apparatus shown in the drawing comprises an electric discharge device I of the gaseous type having an anode 3, a cathode 5 and a control electrode I. The discharge device I is to be controlled in response to an external disturbance of any general type, and when it is energized is to supply current to a load in its anode-cathode circuit. In the embodiment selected for illustration, the discharge device is controlled by a photosensitive device 9 and actuates a relay II in its anode-cathode circuit.

Accordingly, the anode I3 of the photo-sensitive device 9 is connected to the control electrode I of the discharge device I, while the cathode l5 oi the photo-sensitive device is connected to the cathode 5 of the discharge device. To adjust the operation of the discharge device, an impedance, which is illustrated specifically as a resistor ii and may be an inductor or a capacitor, is connected between the anode 3 and the control electrode 1.

Only a direct-current source I9 is available to operate the discharge device I, and for this reason a contrivance must be provided for interrupting the discharge once it occurs without interrupting the supply of potential or reversing it. In the system illustrated, the discharge device I is normally maintained deenergized as long as the photo-sensitive device 9 is energized. The discharge device I becomes energized when the illumination impinging on the photo-sensitive device 9 is interrupted. Accordingly, it is my purpose to provide a contrivance for interrupting the discharge in the discharge device I once it has been initiated by the interruption of the radiation influencing the photo-sensitive device 9 and after the interruption of the radiation has ceased.

To accomplish this purpose, I provide a second electric discharge device 2| of substantially the same type as the first discharge device. The latter is provided with an anode 23, a cathode 25, and a control electrode 21 and is of the gaseous type. A second photo-sensitive device 29 is also provided and its cathode 3| is connected to the control electrode 2! of the second discharge device, while its anode 33 is connected to the anode of the second discharge device. A resistor 35, similar to the resistor connected between the anode 9 and the control electrode 1 of the first discharge device I, is connectedbetween the control electrode 21 and the cathode 25 of the second discharge device 2 I.

The anodes 3 and 23 of the first and second discharge devices are interconnected by a resistor 37 provided with an intermediate tap 39. The terminal taps 4| and. 43 of the resistor are connected to the anodes through the relay I I and a suitable equalizing impedance 45, while the cathodes of the discharge devices are directly interconnected. The direct-current source [9 is connected between the intermediate tap 39 of the resistor 97 and the common connection 41 of the cathodes. A capacitor 49 is connected across the resistor between the anodes of the discharge devices and 2|.

The resistance 35 between the control electrode 2? and the cathode 25 of the second discharge device 2| is so adjusted that under normal circumstances with the second photo-sensitive device 29 energized, the second discharge device is also energized. The photo-sensitive devices 9 and 29 are so arranged that they are simultaneously energized and deenergized. When the light impinging on one of the photo-sensitive devices is interrupted, that on the other device is also interrupted.

Normally, therefore, with light impinging on both photo-sensitive devices, the first discharge device I is deenergized and the second device 2| is energized. The resulting current flowing through the ri ghthand half of the resistor 37, therefore, produces a potential drop between the left-hand plate 5! and the right-hand plate 53 of the capacitor 49, and the left-hand plate is charged positive while the right-hand plate is charged negative. When the light impinging on the photo-sensitive devices 9 and 29 is interrupted, the second discharge device 2| is at first unaffected, but the first discharge device is immediately energized. When so energized, the first discharge device in effect connects the lefthand plate 5| of the capacitor 49 to the cathode 25 of the second discharge device 2!, and since the right-hand plate 53 of the capacitor is already connected to the anode 23, the potential impressed upon the capacitor is thus impressed between the anode and the cathode of the second discharge device 2!. Since this potential is opposite in polarity and substantially equal to the potential tending to maintain the discharge through the second discharge device 2|, the discharge is extinguished and current continues to fiow through the first discharge device as long as the photo-sensitive devices 9 and 29 remain deenergized.

If the photo-sensitive devices 9 and 29 should now become energized, the reverse operation will take place. By the flow of current through the first discharge device I, the right-hand plate 53 of the capacitor 49 was charged positive while the left-hand plate 5! was charged negative. The re-excitation of the photo-sensitive devices 9 and '29 causes the second discharge device to immediately become energized. Therefore, the negative potential of the capacitor 49 is; in effect, impressed directly across the first discharge device I and causes it to become extinguished.

It is to be noted finally that under certain 'circumstances, the two photo-sensitive devices connected in the control circuits of the discharge devices may be replaced by a single one. This object may be accomplished by connecting suitable potentials between the connections of the photosensitive device and the electrode of the discharge devices.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In combination, a first electric discharge de-- vice having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said controlelectrode and a principal electrode of said first device to maintain said device normally nonconductive, a first means responsive to an external disturbance for impressing a potential between said control electrode and one of said principal electrodes such that said first device is rendered conductive, a second electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said second device to maintain said second dcvice normally conductive, a second means responsive to an external disturbance having the same properties as said first disturbance for impressing a potential between the control electrode and a principal electrode of said second device such that said second device is rendered conductive, means for impressing a direct-current potential between the principal electrodes of said discharge devices and means for so coupling said discharge devices that when, on both said responsive means responding to said disturbance, the first device is rendered conductive, the second device is also rendered non-conductive.

'2. In combination, a first electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said first device to maintain said first device normally conductive, a first means responsive to an external disturbance for impressing a potential between said control electrode and one of said principal electrodes such that said first device is rendered non-conductive, a second electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said second device to maintain said second device normally non-conductive, a second means responsive to an external disturbance having the same properties as said first disturbance for impressing a potential between the control electrode and a principal electrode of said second device such that said second device is rendered conductive, means for impressing a potential between the principal electrodes of said discharge devices and means for so coupling said discharge devices that when, on both said responsive means responding to said disturbance, said first device is rendered non-conductive, said second device is also rendered conductive.

3. In combination, a first electric discharge device having a plurality of principal electrodes, a

control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said first device to maintain said first device normally conductive, a first means responsive to an external disturbance for impressing a potential between said control electrode and one of said principal electrodes such that said first device is rendered non-conductive, a second electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said second device to maintain said second device normally non-conductive, a second means responsive to an external disturbance having the same properties as said first disturbance for impressing a potential between the control electrode and a principal electrode of said second device such that said second device is rendered conductive, means, including an impedance, connecting a principal electrode of said second discharge device, for impressing a potential between the principal electrodes of said discharge devices and a capacitor connected in parallel with said impedance for so coupling said discharge devices that when, on both said responsive means responding to said disturbance, said first device is rendered non-conductive, said second device is also rendered conductive.

4. In combination, a first electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said first device to maintain said first device normally conductive, a first means responsive to an external disturbance for impressing a potential between said control electrode and one of said principal electrodes such that said first device is rendered non-conductive, a second electric discharge device having a plurality of principal electrodes, a control electrode and a gaseous atmosphere, means for impressing a potential between said control electrode and a principal electrode of said second device to maintain said second device normally non-conductive, a second means responsive to an external disturbance having the same properties as said first disturbance, for impressing a potential between the control electrode and a principal electrode of said second device such that said second device is rendered conductive, means for impressing a potential between the principal electrodes of said discharge devices and a capacitor so coupling the principal electrodes of said discharge devices that when, on both said responsive means responding to said disturbance, said first device is rendered non-conductive, said second device is also rendered conductive.

5. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, photo-sensitive means connected between a control electrode and a principal electrode of each said discharge devices, means for impressing potentials between the control electrode and the principal electrode and between the principal electrodes of each of said discharge devices to maintain said first device conductive and said second device non-conductive and means for so coupling said discharge devices to each other that when the excitation of said photo-sensitive means is varied to a predetermined extent said second device is rendered non-conductive and said first device conductive.

6. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, photo-sensitive means connected between a control electrode and a principal electrode of each said discharge devices, means for impressing potentials between the control electrode and the principal electrode and between the principal electrodes of each of said discharge devices to maintain said first device conductive and said second device non-conductive, said potential impressing means including means for impressing a direct-current potential between the principal electrode of said discharge devices and means for so coupling said discharge devices to each other that when the excitation of said photo-sensitive means is varied to a predetermined extent said first device is rendered non-conductive and said second device conductive.

'7. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, photo-sensitive means connected between a control electrode and a principal electrode of each said discharge devices, means for impressing potentials between the electrodes of said discharge devices to maintain said first discharge device energized and said second discharge device deenergized and means for so coupling said discharge devices that when the excitation of said photosensitive means is varied to a predetermined extent said first discharge device is deenergized and said second discharge device is energized.

8. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, photo-sensitive means connected between a control electrode and a principal electrode of each said discharge devices, means for impressing potentials between the electrodes of said discharge devices to maintain said first discharge device energized and said second discharge device deenergized, said potential impressing means including means for impressing a direct-current potential between the principal electrodes of said discharge devices, and means for so coupling said discharge devices that when the excitation of said photo-sensitive means is varied to a predetermined extent said first discharge device is deenergized and said second discharge device is energized.

9. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, a first photo-sensitive device connected between the control electrode and a principal electrode or said first discharge device, a second photo-sensitive device connected between the control electrode and a principal electrode of said second discharge device, means for impressing potentials between the control electrodes and the principal electrodes and between the principal electrodes of said discharge devices to maintain said first discharge device conductive and said second discharge device non-conductive and means for so coupling said discharge devices to each other that when the excitation of one said photo-sensitive devices is varied to a predetermined extent, said first discharge device is rendered non-conductive and said second device conductive.

10. Control apparatus comprising a first electric discharge device having an anode, a cathode, a control electrode and a gaseous atmosphere, a second electric discharge device having an anode, a cathode, a control electrode and a gaseous atmosphere, a first photo-sensitive device connected between the control electrode and the cathode of said first discharge device, a second photosensitive device connected between the control electrode and the anode of said second discharge device, means for impressing a direct-current potential between the anodes and the cathodes of said discharge devices, means for maintaining one of said discharge devices energized and the other deenergized for a predetermined excitation of said photo-sensitive devices and means for so coupling said discharge devices that when the excitation of at least one of said photo-sensitive devices is changed said one discharge device is deenergized and said other discharge device is energized.

11. Control apparatus comprising a first electric discharge device having an anode, a cathode, a control electrode and a gaseous atmosphere, a second electric discharge device having an anode, a cathode, a control electrode and a gaseous atmosphere, a first photo-sensitive device connected between the control electrode and the cathode of said first discharge device, a second photo-sensitive device connected between the control electrode and the anode of said second discharge device, means for impressing a direct-current potential between the anodes and the cathodes of said discharge devices, means for maintaining said second discharge device energized and said first discharge device deenergized when both said photo-sensitiv devices are energized and means for so coupling said discharge devices that when said first photo-sensitive device is deenergized, said first discharge device is energized and said second discharge device is deenergized.

12. In combination, a first electric discharge device having a control electrode, a plurality of principal electrodes and a gaseous medium, a second electric discharge device having a control electrode and a plurality of principal electrodes, a first photo-sensitive device connected between the control electrode and a principal electrode of said first discharge device, a second photo-sensitive device connected between the control electrode and a principal electrode of said second discharge device, means for simultaneously energizing and deenergizing said photo-sensitive devices, means for impressing potentials between the con trol electrode and the principal electrode and between the principal electrodes of each of said discharge devices to maintain said first discharge device conductive and said second non-conductive and means for so coupling said discharge devices to each other that when the excitation of said photo-sensitive devices is varied to a predetermined extent said first-discharge device is rendered non-conductive and said second discharge device is rendered conductive.

DEWEY D. KNOWLES. 

